The present invention relates to an apparatus for breaking solid objects, and in particular industrial and domestic waste, with a view to recycling.
Among the many breaking apparatuses in use, the one described in French Patent 2,254,271 is noteworthy for its properties of adapting to objects of various types, which are both fragile and flexible. This apparatus comprises a support hopper with an entry opening in the top and an exit opening in the bottom, a rotor, having a of horizontal axis and carrying two radial knives, and a set of backing knives, integral with the support hopper, between which the knives pass during the rotation of the rotor. These backing knives are grouped in a comb and a backing comb, an object moved by the rotor in its rotation successively encountering the comb and then the backing comb.
The active surface of the backing knives of the comb is straight and toothed, that is to say that it has notches which constitute stops which arrest the movement of an object to be broken.
In practical embodiments in accordance with this patent, the axial gap between a knife of the rotor and the adjacent backing knives of the comb is relatively large, for example 5 to 10 mm, and this part of the apparatus acts as a grinder, while the axial gap between a knife of the rotor and the adjacent backing knives of the backing comb is much smaller, for example 0.5 to 1 mm, so that this part operates as a cutter, whence the name "grinder/cutter" frequently given to this type of apparatus.
The apparatus operates at relatively low rotational speeds of the rotor, for example of the order of 20 r.p.m., so that it is not very noisy. When there is an object which is too strong to be ground, rotation in the opposite direction through approximately one revolution makes it possible to remove it through an auxiliary orifice situated beyond the backing comb, in the normal rotation direction.
French Patent 2,127,685 describes a fairly similar apparatus, except that the backing knives are mounted on a common "anvil", which can pivot with respect to the support hopper about an axis parallel to that of the rotor. This arrangement has the advantage that, when there is an excessively strong object, the anvil, with the backing knives, moves away from the rotor to let this object pass. A return jack then returns the anvil to the normal position. This system is combined with a smooth shape, curved toward the rotor, of the active face of the backing knives, intended to facilitate removal of ungrindable objects, but reduces the efficiency of the apparatus for breaking other objects.
U.S. Pat. No. 4,917,310, which corresponds to the preamble of claim 1, describes an apparatus which differs from that of French 127,685 in that the backing knives are straight, and especially in that the backing knives are movable independently of each other, and provided with return means which may consist of fluidic jacks connected to a pneumatic accumulator. This device provides some improvement in efficiency, but this is outweighed by an increase in its complexity.
Soviet Union Patent 697,186 describes a device for breaking up blocks of reinforced concrete, in which these blocks, sliding over a planar support, are struck by a tool driven in a reciprocating vertical movement using an eccentric device. It seems that the concrete is disintegrated by the repeated impacts, and releases the reinforcement irons. Nothing suggests that these reciprocating movements can be effective in a device operating by cutting for breaking solid objects which may exhibit some degree of flexibility, such as waste, and in preventing clogging.